1. Field of the Invention
The present disclosure relates generally to a method and apparatus for selecting a group of base stations in a communication system, and in particular, to a method for selecting a group of base stations when installing a new base station or extending or optimizing a network in a wireless communication system operating with Remote Radio Heads (RRHs) deployed in a distributed manner on the network.
2. Description of the Related Art
Communication networks are designed to maximize system coverage and capacity efficiency with radio units installed in a distributed manner within a network installation space and using cooperative and integrative scheduling. Such network design policies alleviate coverage holes caused by geographical characteristics and other problems caused by legacy network designs with the addition of extra radio units.
Further, such network design policies may fulfill the intended throughput maximization only with the operation of a centralized integrated scheduler, which allocates radio resources in consideration of radio environments of the users connected through a plurality RRHs managed by the base station, other than allocating the resource to the users independently.
More specifically, RRHs may be used to transmit the same data to a user to obtain the diversity gain under the control of the centralized scheduler. Also, some users may be denied resource allocation in order to avoid interference for another user served by neighbor RRHs.
If it is determined that the users are far enough away to use the same resource without interfering with each other, the entire network throughput may be increased by allocating the same resource space to a plurality of users. Basically, the integrated scheduler makes a scheduling decision to maximize the Proportional Fairness (PF) of the entire network.
Using the integrated scheduler makes it possible to apply the PF scheduling technique, which is used for each base station to perform radio resource allocation within each cell in the legacy cellular system, to groups of cells, in order to integrally manage multiple cells to optimize the radio resource allocation performance for a plurality of cells under one scheduler, other than one cell.
However, the integrated scheduler is also restricted in the number of base stations that may be managed, by complexity and system load.
Accordingly, the entire network requires a plurality integrated schedulers, which increases the complexity on how to combine the base station for efficient management of the integrated scheduler to increase PF of the entire network.
The scheduling method of the legacy cellular system or distributed base station system performs scheduling to the user connected per cell independently.
Accordingly, the radio resource is allocated to maximize the PF per cell, and the adjacent cells avoid allocating the transmit power or resources at the same time in the inter-cell interference cancellation and Multi-User Multiple Input Multiple Output (MU-MIMO) techniques.
However, the above-described techniques attempt to maximize the throughput of the base station as the transmission source, and thus, if they are used along with the centralized scheduler, this may actually reduce system throughput.